The following description of background art may include insights, discoveries, understandings or disclosures, or associations together with disclosures not known to the relevant art prior to the present invention but provided by the invention. Some such contributions of the invention may be specifically pointed out below, whereas other such contributions of the invention will be apparent from their context.
Wideband communication systems, such as LTE systems, have a significantly wider bandwidth than in previous wireless systems. The LTE system supports the application of multiple antenna techniques, e.g. MIMO and beam forming. A beam forming algorithm normally assumes that an antenna array has no errors and that its multi-channel transceiver has an identical transfer function for each transceiver chain. However, due to mechanical and electrical variations in the radio frequency components such as amplifiers, mixers and cables, the spatial signature of a baseband receive/transmit signal may be different from an actual radio frequency receive/transmit signal. As a result, transfer functions of the radio frequency transceivers may differ from each other, i.e. amplitude, time and phase deviations may appear between different antenna branches. Thus, it is important to perform antenna calibration to compensate the deviations between the different antenna branches to achieve an expected antenna gain.